The present invention relates to a device for determining a rotary angle. In particular it relates to a device which has two bodies which are movable relative to one another and at least one sensor coil through which alternating current flows and whose inductive and alternating resistance value is changed due to relative change of the size of the regions of the bodies associated with the coil.
A device of the above mentioned general type is disclosed for example in the German document DE-OS 39 16 864.6. The coil body disclosed in this reference has a slot at its end side so that two semi-circular cores are produced. A sensor coil is wound on each of the cores and is in operative connection with a sleeve body. The sleeve body has a slot or zone of electrically non-conductive material. Since the sensor operates in accordance with the so-called eddy current principle, the measuring signal can be distorted by eventual wobbling movements which change the distance between the coil and the inner side of the sleeve body. This negatively influences the accuracy of the measuring signal and thereby the determination of the rotary angle.
The German document DE-OS 38 24 535.3 discloses another device for determination of a rotary angle, which operates in accordance with the eddy current principle. In this document the sleeve body is arranged on the coil body. However, here also the measuring signal can be distorted due to frictional losses between these parts.